The invention provides a wheel lock-up prevention device for compressed air operated wheel brakes in a motor vehicle comprising a common control of the brake pressure in the brake cylinders of the motor vehicle axle and more particularly an assembly wherein a common 3/2-way valve is inserted into the brake line leading to the two brake cylinders. Further the brake line in such assembly is conducted downstream of the 3/2-way valve via a separate branch line to an individual brake cylinder wherein an individual 2/2-way valve is inserted into each branch line as defined in U.S. Pat. application Ser. No. 800,598, filed May 25, 1977, now U.S. Pat. No. 4,153,307.
The use of double diaphragm valves for wheel brake lock-up prevention apparatus is already known from DT-OS 2 234 229. The one diaphragm disclosed therein is subjected to a brake line passage pressure and the other diaphragm guards an outside air connection. However, an advantageous combination of such a diaphragm valve with an electromagnet and a multiple application of such a combination with its variations are not disclosed by this concept.